Heavy duty liquid detergent



United States Paten Delaware No Drawing. Filed Apr. 17, 1964, Ser. No. 360,765

6 Claims. (Cl. 252-137) This invention relates to heavy duty liquid detergents and especially to those having low cloud points.

In recent years built liquid detergents have been gaining favor for washing soiled clothing, for washing dishes and for other purposes requiring an eifective detergent. A built detergent is one which contains, in addition to the surface active agent, a soluble salt capable of sequestering calcium and magnesium ions of hard water and also capable of increasing the level of detergent effectiveness of the surface active agent. Build liquid detergents have, to some extent, replaced granular built detergents for various reasons. These reasons include: complete freedom from dustiness, compact package, convenience in pouring and measuring, and simplification of manufacture.

The problems which have to be overcome in formulating built detergents in clear homogeneous liquid form are mainly the problems of incorporating sufficient surface active agent and builder into the same solution. In current practice an anionic sulfated or sulfonated compound is ordinarily used as surface active agent, and potassium pyrophosphate is used as builder. Various surface active agents, hydrotropes and solvents are employed to increase their compatibility.

US. Patent No. 2,920,045 is directed to a liquid detergent of anionic sulfonate, builder, aqueous alcohol medium and as a suspension agent: wax, colloidal silicate or silica, and urea or thiourea.

US. Patent 2,947,702 prepares a liquid detergent from sodium dodecylbenzene sulfonate, potassium pyrophosphate, and as solubilizing agent: a combination of ethylalcohol, certain hydroxy carboxylic acids and urea.

US. Patent No. 3,085,982 is directed to a heavy duty liquid detergent of certain tertiary amine oxides, anionic sulfonate detergent, potassium pyrophosphate, and as a hydrotrope certain lower benzene sulfonates.

Studies have been made on liquid detergents consisting essentially of anionic sulfonate detergents, potassium pyrophosphate and lower benzene sulfonate hydrotrope. It is possible to prepare at room temperature, 75-80 F., clear solutions containing as much as detergent, potassium pyrophosphate and 7.5% hydrotrope. (All percentages herein are weight percent based on total composition, i.e., liquid detergent.) However, laundry tests indicated more pyrophosphate was needed. A composition containing 15% detergent, pyrophosphate and 7.5% hydrotrope was cloudy, i.e., not clear, at room temperature.

An object of the invention is a heavy duty liquid detergent which is clear at ordinary usage or storage temperature. Another object of the invention is a heavy duty liquid detergent which contains an exceptional amount of builder and is clear at ordinary usage or storage temperatures. Other objects will become apparent in the course of the detailed description of the invention.

It has been discovered that a combination of urea and lower sulfonate is remarkably more effective as a hydrotrope in liquid detergents than is either of these materials alone. The liquid detergent composition of the invention employs a combination of urea and lower sulfonate as a hydrotrope in order to obtain clear solutions, at ordinary usage and storage temperatures.

The heavy duty liquid detergent of the invention is made up of water soluble, anionic sulfonate detergent, about 13-25%; potassium pyrophosphate, about 20-35%; a combination of lower sulfonate and urea as l1ydrotrope, 5-l0%; and the remainder substantially water.

Various other ingredients may be added as desired including compatible perfumes, coloring materials, corrosion or anti-tarnishing inhibitors, e.g., silicates, germicides, bleaching agents, optical bleaches or fluorescent brighteners, and the like. It is preferred to add a minor amount, such as %5% by weight, of a soil anti-redeposition agent, e.g., cellulose ethers. Suitable examples are methyl-, ethyl-, and hydroxyethylcellulose, alkali metal carboxymethylcellulose. In exceptional cases, a lower alcohol may be present.

Any anionic sulfonate detergent which possesses the requisite water solubility may be used. It is preferred to use: The alkane sulfonates having 12-18 carbon atoms and especially the n-alkane sulfonates, e.g., having about 16 carbon atoms. These alkane sulfonates may be of one carbon number or a mixture of carbon numbers as normally exists when the sulfonate is made from a petroleum fraction.

Also, the alkylaromatic sulfonates having 8-16 alkyl carbon atoms; desirably the alkylbenzene sulfonates such as dodecylbenzene sulfonate and especially the n-alkylbenzene sulfonates.

The composition of the invention contains about 13- 25% of the defined detergent sulfonate and more usually about 15-20%.

The primary builder in the composition of the invention is potassium pyrophosphate. Minor amounts of other builders may be present. The composition of the invention contains about 20-35% of the pyrophosphate and more usually about 25-30%.

A homogeneous clear solution at ordinary usage and storage temperatures is obtained by using as hydrotrope a combination of urea and lower sulfonate. The combination gives a lower cloud point, in a given composition, than the same amount of either material alone. Beneficial results are obtained with even a minor amount of either material present, e.g., 99% urea and 1% lower sulfonate; or 1% urea and 99% lower sulfonate. Usually the combination will contain about 25-75% of urea and about -25% of lower sulfonate. It is preferred that the combination contain about 50-75% of urea and about 50-25% of lower sulfonate.

These lower sulfonates have no significant detergent property. Of particular interest are the lower alkane sulfonates having 4-8 carbon atoms, e.g., hexane sulfonate. The lower benzene sulfonates having 0-4 alkyl carbon atoms, e.g., benzene sulfonate, toluene sulfonate, xylene sulfonate, and n-butyl sulfonate are preferred.

These anionic detergents and lower sulfonates are used in the form of their water-soluble salts, such as the alkali metal, alkaline earth metal, ammonium, amine, and alkylolamine salts. While the sodium, potassium, ammonium and alkylolamine (e.g., mono-, di-, and triethanolamine) salts are preferred ordinarily, other salts such as the lithium, calcium, and magnesium salts may be used if desired. For general use, it is preferred to use the sodium and potassium salts.

Illustrations Embodiments of the composition of the invention, and certain comparative compositions, and their respective cloud points are set out below.

The detergent component was a sodium n-alkane sulfonate having about 16 carbon atoms derived from a petroleum fraction by conventional procedures. The potassium pyrophosphate was a commercial grade material. The urea, sodium toluene sulfonate and sodium xylene sulfo- 3 nate were commercially available materials. For convenience these detergent compositions consisted only of the above named detergent sulfonate, pyrophosphate. hydrotrope and water.

B Sodium toluene sulfonate. b Sodium xylene sulfonate.

The above results show conclusively the unobvious benefits gained by using a combination hydrotrope. Composition 3 has a cloud point lowering of 18 F. over the lower sulfonate alone, and 5 F. over urea alone. Composition 4 has a cloud point decrease of 46 F. over the lower sulfonate alone and 78 F. over urea alone. The result with Composition 5 is consistent with the results of Compositions 3 and 4.

Thus having described the invention, what is claimed is:

1. A liquid detergent composition consisting essentially of:

(a) water soluble, anionic alkane sulfonate detergent having about 1218 carbon atoms, about 13-25 (b) potassium pyrophosphate, about 35%;

(c) hydrotrope, about 510%, where said hydrotrope consists of benzene sulfonate having 0-4 alkyl carbon atoms, 75%, and urea, 75-25%; and

(d) the remainder substantially water.

2. The composition of claim 1 wherein said sulfonate detergent is n-alkane sulfonate having about 16 carbon atoms.

3. The composition of claim 1 wherein said benzene sulfonate is sodium toluene sulfonate.

4. The composition of claim 1 wherein said benzene sulfonate is sodium Xylene sulfonate.

5. The composition of claim 1 wherein said hydrotrope has 50% of urea.

6. A heavy duty, liquid detergent consisting essentially of:

(1) sodium alkane sulfonate having about 16 carbon atoms, about 15%;

(2) potassium pyrophosphate, about 30%;

(3) urea, about 5%;

(4) sodium toluene sulfonate, about 2.5%; and

(5) the remainder substantially Water.

References Cited by the Examiner UNITED STATES PATENTS 1/1960 Hearn et al 252--137 8/1963 Wixon 252137 OTHER REFERENCES LEON D. ROSDOL, Primary Examiner.

SAMUEL H. BLECH, Examiner.

S. E. DARDEN, Assistant Examiner. 

1. A LIQUID DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF: (A) WATER SOLUBLE, ANIONIC ALKANE SULFONATE DETERGENT HAVING ABOUT 12-18 CARBON ATOMS, ABOUT 13-25%; (B) POTASSIUM PYROPHOSPHATE, ABOUT 20-35%; (C) HYDROTROPE, ABOUT 5-10%, WHERE SAID HYDROTROPE CONSISTS OF BENZENE SULFONATE HAVING 0-4 ALKYL CARBON ATOMS, 25-75%, AND UREA, 75-25%; AND (D) THE REMAINDER SUBSTANTIALLY WATER. 